Greg Norvell's 1968 Firebird 400 Stroker: Knocking on 11s Door
|by Greg Norvell|
|PSP Webmaster--This writing was originally posted by Greg on the Restoration Forum. It was so enlightening that I earmarked it for inclusion with his engine feature. Putting power to the ground is the ultimate goal. Greg tells us about his ungoing efforts in this area.|
|Knocking on 11s door.
I have read a couple of peoples performance improvements as they go to the track overtime and thought it was pretty cool. Here is mine.
Spring 2003: Trying to do anything to improve the bottom end power in my 400. The problem was a poor combination of parts (low compression, with too big of cam, with not enough gear). I switched to a smaller cam and it ran a little better, but I ended up loosing the motor a few months later. I decided to build my dream motor, aka torque monster. I purchased a 4.25 rotating assembly from Jim Butler and had JBP port the #16 heads to flow 250 cfm at .5. By the spring of 2004 everything was together and running. I had the following:
Car: 1968 Firebird 400
Block: 1968 Pontiac 400, YT
Bore and Stoke: 4.155 bore 4.25 stroke
Crankshaft and Rods: Eagle cast crankshaft 4.25" stroke with Eagle H-beam 6.8" Rods, all reciprocating parts are balanced, dished Ross pistons dished 26.5 cc for 9.4 compression from JBP
Heads: 1968 #16 with Ferrea valves, 2.11/1.77, Comp Cams magnum rockers 1.52 rocker arms, aluminum fill in heat cross over, ARP head bolts, Comp 995 valve springs installed at 1.700", 76 cc combustion chambers, ported by Jim Butler Performance
Corrected Flow Intake @ 28" of H2O - exhaust flows 70% to 75%
Camshaft: Comp Cams XE274 230/236 .488/.491 with Comp Cams push rods CCA-7786
Intake: RPM ported to match the heads
Carb: Holley 750 with vacuum secondaries
Fuel Pump: Holley, 110 gph
Timing Gear and Chain: Summit True Roller SUM-86612
Oil Pump: Sealed Power high pressure - SLP-224-43364S 20 lbs at idle, 10W-30 Mobile synthetic oil
Ignition: MSD billet distributor, MSD 6A ignition, 18 degrees initial timing with 36 degrees of total advance at 2,000 RPMs, MSD 8mm spark plug wires - MSD-8364
Damper: JBP-872031 SFI Approved
Radiator: Dessert Cooler with a Flex-a-lite fan
Exhaust: 1 5/8" Hooker Competition headers, Flowmaster 2 1/2" system with H-pipe, tail pipes exit behind rear wheels
Chassis: Comp engineering bolt-on sub frame connectors CEE-3112 welded
Transmission/Converter: TH 400 with TCI shift kit/TCI 11" low stall 2,000 RPMs - TCI-240920 Converter will flash to 2,400 rpms at the track with ET Streets
Rear End: Currie Ford 9" with 31 spines, 3.25s and Auburn posi
Vehicle Weight: 3,700 lbs with driver
Tires/Wheels: Front 15X7 with BFG Comp TA HR4 215/60, Back 15X8 with 255/60 BFG TAs
3/8/2004 Maiden Voyage 13.75 @ 101.19 . when I got the slip and I saw how slow my car was I almost cried. I was so disappointed. My car was overheating badly even though it was cold; however, I did manage to run a best 13.65 @ 102.96....a small ray of hope. I had absolutely no traction; my best 60 was a 2.196. I was shifting at 5,600 RPMs.
I had purchased the BeCool radiator/fan to eliminate the overheating problem. I think I kind of panicked on this one, but I didnt want to overheat my new $$$ motor. I put about 100 lbs in the trunk and started to play around with my shift points. My best for the day was: 60 2.085, ET 13.485, MPH 103.11. I dropped my shifts down to 5,100 to 5,400 RPMs.
I figured out my carb was only opening up about 70% to 80% and fixed that issue. Periodically, I had stumbling issues at the end of 1st gear. I couldnt figure out what was going on. I met David Kawallek and I was telling him my issue. He suggested that I lower my fuel pressure from 9 lbs to 6 lbs. which solved the problem. My best for the day was: 60 2.05, ET 13.36, MPH 104.25. I told him that my expectations were much higher and he told me to keep on tuning and get some decent tires and I will be in the 12s in no time(just what I needed to hear). I shifted at 5,400 all night. I was hooked on drag racing and going faster after running the 13.36.
ET Streets on Bart rims. The car hooked so good it bogged down. My best for the day was: 60 2.106, ET 13.463, MPH 104.34. I couldnt believe I actually slowed down with the ET Streets. I had no clue what was wrong.
More of the same. My best for the day was: 60 1.989, ET 13.41, MPH 105.69. With the exception of one decent launch, my 60 times sucked. I did play with the timing and settled on 33 degrees of total advance. After talking with David and reading all of the write ups on PSP, I thought 36 might be too much. On the last run, I decided to remove the air cleaner. I had noticed that week that the air cleaner only cleared the chock tower by 1/8. I picked up 2.4 MPH. I figured I needed more converter, so I gave JBP a call and spoke with Jim. Jim told me the converter was fine and the cam started pulling at 1,800 rpms and the problem was the accelerator pump circuit. David also suggested I launch from idle.
I jumped up to a .31 squirter and a pink cam from .28 and a white cam. What a difference that made! Launching from idle moved the stall up to 2,400 rpms from about 2,200 rpms when launching from 1,800 rpms. I was also was running really rich up to this point and leaned the carb about 6 jets (to its factory set up). Plus, I purchased a 1/2 taller element which gave me additional clearance above the choke tower, but put me within a 1/4 of hitting the hood. My best for the day was: 60 1.938, ET 13.057, MPH 105.80. I shifted at 5,200 rpms.
David recommended I clean out the carb after the burnout (by slipping the car into neutral and revving the motor a few times) and air up the front tires to 40 lbs. It worked. My best for the day was: 60 1.919, ET 12.994, MPH 106.23. I played with my shift points and found 5,300 to be the sweet spot.
Everyone from David to Jim Hand, told me to ditch the Holley 750 with vacuum secondaries. I was contemplating what I should buy. I was telling the store manager at OReillys to get his opinion and he told me that he had a 750 dp I could try if I wanted too (I figured out it was a 650 a few months later). If I liked it, he would sell it to me cheap. I put it on and could not believe how much the motor woke up. It was awesome. I was out in my usual remote spot enjoying the new found power when my rear u-joint gave way. I sounded like a bomb; I thought I had lost the motor. I guess I had over tightened the u-bolt and crimped it enough to heat up and break loose. Expensive lesson, but I was so giddy about the new found power I didnt care.
WOW, what the hell was wrong with the other carb? I had the lightest spring in it. My best for the day was: 60 1.900, ET 12.496, MPH 110.94. I was on cloud 9. I never thought I would be able to run this fast with a 3.25 gear and 2,400 stall.
More of the same. My best for the day was: 60 1.900, ET 12.533, MPH 110.85. I submitted for the 1 to 1 club and was turned down.
Best traction of the year, but the air was terrible with a 10 mph headwind. My best for the day was: 60 1.881, ET 12.5, MPH 110.55.
Tried a friends 825 mighty demon, but the air was poor and I couldnt get my distributor to stay put. The timing kept creeping up to 36 degrees. My best for the day was: 60 1.94, ET 12.567, MPH 110.72.
My engine started to die like it ran out of fuel. It wouldnt run unless it was above 1,800 rpms and then not at all. It wasnt fuel related. I put in a new distributor cap, rotor, spark plug wires, pick up, and spark plugs. It still would not fire and stay running. I talked to MSD on a daily basis and we couldnt figure anything out. I then separate my shoulder (3rd degree) and had to have a friend (who built the motor) come and pick up the car. He tried a new coil and she fired right up. This happened over the course of a couple of months time.
Secondary divider cut per Jim Hands book. With a 12 mph head wind, my best for the day was: 60 1.939, ET 12.537, MPH 110.75.
With better weather conditions, my best for the day was: 60 1.906, ET 12.315, MPH 111.78. I submitted and was accepted into the 1 to 1 club.
With the NHRA lowering the requirement for a roll bar to 11.49, I decided to do a few upgrades: new Pro Systems 800 DP, Continental Tight 10 3,200 stall converter, and Cal Tracks.
With 10 mph head wind and launching from 1,400 RPMs my best for the day was: 60 1.80, ET 12.201, MPH 110.45. I was spinning for the first 20ft.
With bigger burnouts and better air, my best for the day was: 60 1.748, ET 12.18, MPH 112.05. I am still spinning the first 10 ft. I call Cal Tracks and they tell me to try 1/4 turn preload the next time out. I take off my shocks to adjust and find that one is shot. I order the RS 9000 Rancho shocks.
5 mph to 15 mph headwind/crosswind that was so bad, I had to abandon 3 runs on the big end. My best for the day was: 60 1.726, ET 12.002, MPH 112.1. I had been running in the 12.2 range at 110 and decide to jump 3 jets on each side. I run a single wire 02 sensor and knew I was running a little lean 750 mv vs. 850 mv to 900 mv. This jet change made a big difference it put me at 850 mv. In addition, I started to launch off idle again. Unfortunately, I was unable to try step up again in jet size do to time constraints. I am still spinning the first 8 to 10 ft. The stock multi leaf springs are not allowing the car to squat at all. The next time out; hopefully, it will be good air with no headwind and I will be in the 11s.
|When Greg's car finally breaks into the 11s, and it will, this writing will be updated.--PSP|